Integumentary System

Main functions Organs/parts/cells and their functions Diseases and disorders

Main functions

Multiple roles in homeostasis

(e.g. temperature change, dehydration) Protects against invasion of infectious organisms, sunburn Protects the body’s internal tissues and organs Maintains the body’s form Generates vitamin D Stores fats, water, glucose and vitamin D

Major organs

HairSkin Nail

Skin It's your body's largest organ

Average surface area 1.8-2.0m² (19.4-21.5ft² )

Releases around three gallons of sweat in a hot day

There are at least five types of receptors in the skin that respond to pain and to touch

White skin appeared just 20,000 to 50,000 years ago, as dark-skinned humans migrated to colder climes and lost much of their melanin pigment.

Three layers or structures of the skin

Epidermis

Dermis and hypodermis

Sweat and oil glands; hair and nails

Epidermis cornified layer (stratum corneum)

clear/translucent layer(stratum lucidum, only

in palms and soles)

granular layer (stratum granulosum)

spinous layer (stratum spinosum)

basal/germinal layer

(stratum basale/

germinativum)

Cells of epidermis

95% cells are keratinocytes Major function is the defense against environmental damage

(pathogens, heat, UV radiation and water loss)

Melanocytes ( melanin-producing cells ) Langerhans cells (antigen-presenting immune

cells) Merkel cells (oval receptor cells ) Inflammatory cells (a cell participating in the

inflammatory response to a foreign substance. )

First and last layers of epidermis

basal/germinal layer Cell growth of keratinocytes, attached to basement

membrane. Melanocytes and Merkel cells also can be found in this layer.

cornified layer Keratinocytes are presented at final step of differentiation

(corneocytes), surrounded by keratin proteins envelope. Most of the barrier function are here

Dermis

Two layers: Stratum papillare and Stratum reticulare

Stratum papillare This region is composed of loose connective tissue with

network of blood capillaries and  Meissner's corpuscles (type of mechanoreceptors sensitive to light touch)

Stratum reticulare Is composed of dense irregular connective tissue with

collagen, elastic and reticular fibers (strength, extensibility, and elasticity)

Hypodermis

 Hypodermis or subcutaneous tissue

 In hypodermis fibroblasts, adipose cells and macrophages can be found

 Is used mainly for fat storage

In arthropods, the hypodermis is an epidermal layer of cells that secretes the chitinous cuticle

Glands of skin

Sebaceous Glands Sweat Glands Ceruminous glands Mammary Glands

Sebaceous Glands

Secrete an oily/waxy matter, called sebum, to lubricate and waterproof the skin and hair

Greatest abundance on the face and scalp

Sebaceous Glands Diseases Acne

Hyperplasia - disorder of the sebaceous glands in which they become enlarged

Sebaceous cysts

Sebaceous adenoma - a slow-growing tumour

Sebaceous gland carcinoma - aggressive malignant cutaneous tumor

Sweat Glands

Apocrine Eccrine

Apocrine glands

produce a viscous and odorous secretion. They begin secreting at puberty

discharge in the canals

of hair follicles

may also contain pheromones

Eccrine glands smaller than apocrine

sweat glands, and they do not extend as deep into the dermis

discharge their secretions directly onto the surface of the skin

• highest density (>250 glands/cm2) being on soles, palms, and scalp

Sweat Glands Diseases Hidradenitis - The inflammation of a

sweat gland (usually of the apocrine type)

Hyperhidrosis - Excessive sweating

Hypohidrosis - diminished or absent perspiration

Miliaria - A syndrome of cutaneous changes associated with sweat retention and extravasation of sweat at different levels in the skin.

Ceruminous glands

specialized sweat glands located in hypoderm

drain into the guard hairs

produce cerumen, or earwax, by mixing their secretion with sebum and dead epidermal cells

Ceruminous glands diseases

Benign tumors

(e.g. ceruminous adenoma - tumour of the external auditory canal in adults, 1% of all external ear tumors)

Malignant tumors

(e.g. Mucoepidermoid carcinoma - most common type of malignancy in adults. Can also be found in other organs, as bronchi, lacrimal sac and thyroid.

Mammary Glands

An organ in women that produces milk

Milk is produced by cuboidal cells surrounded by myoepithelial cells – thin layer above the basement membrane

Mammary Glands Diseases

Fat necrosis - firm nodule in the breast

Fibrocystic change - most common disorder

Gynecomastia - bilateral breast enlargement in the male

Fibroadenoma: most common benign tumor

Breast cancer - most common type of cancer in women

Some other common Skin Diseases

Melanoma

Eczema

Otitis Externa

Skin Cancer

Hair facts The fastest growing tissue in the body

90% of scalp hairs are growing and 10% are resting

Female hair grows more slowly

Lifespan of hair: 2 to 7 years

A single hair has a thickness of 0.02 - 0.04mm

The average scalp has 100,000 hairs

It is normal to lose 100 hairs per day from the scalp

A single hair can support up to 100 grams in weight and a whole head of hair could support up to 12 tonnes - the equivalent of two African elephants!

Hair Parts

the hair root

the hair shaft

Hair is composed primarily of proteins (88%). These proteins are of a hard fibrous type known as keratin.

Hair root

Is surrounded by a pouch like structure called hair follicle

The terminal part of the hair follicle is called a hair bulb (formed by actively growing cells )

• consist of: • Fibrous connective tissue• External/internal root sheath

Hair root

At the base of each hair bulb is the dermal papilla containing a vessel tuft (essential for the nourishment of the growing hairs).

Melanocytes – produce pigment melanin.

Receptors for the male hormones - androgens, are located on the cells of this structure.

Hair shaft

The newly divided hair cells in bulb push the previous cells up. The cells, which move upwards, die slowly forming hard hair shaft.

Has three layers: Cuticle Medulla Cortex

Hair diseases and disorders

Mainly associated with the follicles of the hair

Hypertrichosis - an abnormal amount of hair growth on the body

Alopecia Areata - one of the most prevalent hair loss diseases

Nails Actually the same as hair

Nails grow at the rate of 0.1 mm daily

Women's nails grow slowly

Toe nails are about twice thicker than finger nails

The fastest growing nail is on the middle finger. The slowest – on the thumbnail

Nails reflect your health status

(I) Nail structure 6 parts: The root (germinal matrix) - produces most of the

volume of the nail and the nail bed.

Nail bed (sterile matrix) - part of the nail matrix. Contains the blood vessels, nerves, and melanocytes. Adds material to the undersurface of the nail making it thicker

Nail plate - actual

fingernail, made of

translucent keratin

(II) Nail structure 6 parts :

Eponychium (cuticle) – fuse skin and nail plate, providing waterproof barrier

Perionychium (paronychial edge) - the skin that overlies the nail plate on its sides

Hyponychium -the area between the nail plate and the fingertip

Nail diseases

Fungal infection (Onychomycosis)

Beau's Lines

Nail Lifting (Onycholysis)

Nail Splitting (Onychoschizia)

Bacterial infection (Paronychia)

Integumentary System Functions Multiple roles in homeostasis (e.g. temperature change, dehydration) Protects against invasion of infectious organisms, sunburn Protects the body’s internal tissues and organs Maintains the body’s form Generates vitamin D Stores fats, water, glucose and vitamin D

Skin

Hair

Nail

Thank you for your attention!

Sources http://en.wikibooks.org/wiki/Human_Physiology/Integumentary_System#Glands http://emedicine.medscape.com/article/1960501-overview http://www.medicalglossary.org/skin_diseases_sweat_gland_diseases_definitions.html www.gwu.edu http://www.hshairclinic.co.uk/hair-loss/all-about-hair/hair-structure/ http://www.summerwinds.com/downloads/howtodocs/ANATOMY-OF-HAIR.pdf http://dermatology.about.com/cs/nailanatomy/a/nailanatomy.htm